Aromatic polyethers, including polyether sulfones are known. These resins are characterized by their flame resistance, mechanical properties and their oxidative and dimensional stability at elevated temperatures. It has long been recognized that because of the absence of functional groups from their respective structures polyether and polysulfones are not easily copolymerized. A process for the preparation of block copolymers of polycarbonate and polysulfones has been disclosed in the article Bisphenol-A-Polycarbonate Bisphenol-A-Polysulfone Block Copolymers by James E. McGrath et al in Polymer Engineering and Science August 1977 Vol. 17, No. 8 PP 647. Accordingly, a low molecular weight hydroxy-terminated polysulfone has been first produced by the condensation of excess of the sodium salt of BPA with dichlorodiphenyl sulfone. The oligomer was then dissolved in a mixture of methylene chloride and pyridine. Addition of BPA and phosgene resulted in the formation of a block copolymer. European Patent Application 353,478 disclosed polyether-polycarbonate copolymers and their preparation. The copolymers are prepared by contacting an activated polyaryl ether thioether polymer with a polyaryl carbonate.
In order to facilitate copolymerization it has been proposed to use polyethers which contain functional groups, for instance ester groups. An ester group-containing aromatic polyether has thus been disclosed in European Patent Application 445 409. Accordingly, the preparation of the aromatic polyether is carried out by reacting together in a one step process a diflourobenzophenone, bisphenol-A and an ester bisphenol (EBP). This process has been found to be suitable also where the benzophenone has been replaced by a difluorodiphenyl sulfone (DFDPS). The drawback to this process is the high cost of DFDPS. An attempt to carry out the process with the corresponding chloro compound, dichlorodiphenyl sulfone, was unsuccessful as only low molecular weight product results.